Struct BackwardUserIterator

pub struct BackwardUserIterator<I: HummockIterator<Direction = Backward>> {
    iterator: I,
    just_met_new_key: bool,
    last_key: FullKey<Bytes>,
    last_val: Bytes,
    last_delete: bool,
    out_of_range: bool,
    key_range: UserKeyRange,
    read_epoch: HummockEpoch,
    min_epoch: HummockEpoch,
    _version: Option<PinnedVersion>,
    stats: StoreLocalStatistic,
}

BackwardUserIterator can be used by user directly.

Fields

iterator: I

Inner table iterator.

just_met_new_key: bool

We just met a new key

last_key: FullKey<Bytes>

Last user key

last_val: Bytes

Last user value

last_delete: bool

Last user key value is deleted

out_of_range: bool

Flag for whether the iterator reaches over the right end of the range.

key_range: UserKeyRange

Start and end bounds of user key.

read_epoch: HummockEpoch

Only reads values if epoch <= self.read_epoch.

min_epoch: HummockEpoch

Only reads values if ts > self.min_epoch. use for ttl

_version: Option<PinnedVersion>

Ensures the SSTs needed by iterator won’t be vacuumed.

stats: StoreLocalStatistic

Store scan statistic

Implementations

impl<I: HummockIterator<Direction = Backward>> BackwardUserIterator<I>

pub fn new( iterator: I, key_range: UserKeyRange, read_epoch: u64, min_epoch: u64, version: Option<PinnedVersion>, ) -> Self

Creates BackwardUserIterator with given read_epoch.

fn out_of_range(&self, key: UserKey<&[u8]>) -> bool

fn reset(&mut self)

pub async fn next(&mut self) -> HummockResult<()>

Gets the iterator move to the next step.

Returned result:

• if Ok(()) is returned, it means that the iterator successfully move to the next position (may reach to the end and thus not valid)
• if Err(_) is returned, it means that some error happened.

pub fn key(&self) -> FullKey<&[u8]>

Returns the key with the newest version. Thus no version in it, and only the user_key will be returned.

The returned key is de-duplicated and thus it will not output the same key, unless the rewind or seek methods are called.

Note: before call the function you need to ensure that the iterator is valid.

pub fn value(&self) -> &[u8]

The returned value is in the form of user value.

Note: before call the function you need to ensure that the iterator is valid.

pub async fn rewind(&mut self) -> HummockResult<()>

Resets the iterating position to the beginning.

pub async fn seek(&mut self, user_key: UserKey<&[u8]>) -> HummockResult<()>

Resets the iterating position to the first position where the key >= provided key.

pub fn is_valid(&self) -> bool

Indicates whether the iterator can be used.

pub fn collect_local_statistic(&self, stats: &mut StoreLocalStatistic)